The long goal of this project is to provide further understanding of the physiological significance of inactive renin. Active and inactive renin will be measured in plasma, renal hilar lymph and renal tissue of dogs and rats during chronic stimulation or suppression of the renin-angiotensin system. Acute changes in the renin release will be superimposed on the chronic state. Inactive renin will be activated by dialysis of plasma, lymph or tissue extracts at pH 3.3. The rate of secretion, concentration in plasma and metabolism of both forms of renin will be determined.